This invention relates to tufting machines and more particularly to mounting apparatus for supporting the needle bar of a tufting machine for transverse or lateral movement relative to the direction of movement of the base material.
In the art of tufting one or more rows of yarn carrying needles are reciprocably driven through a base material fed through the machine to form loops that are seized by loopers or hooks oscillating below the base material in timed relationship with the needles.
The needles are typically mounted in a needle bar supported at the end of a plurality of push rods constrained for reciprocatory motion toward and away from the loopers or hooks. In those machines having a sliding needle bar arrangement, i.e., wherein the needle bar is controllably driven by pattern means transverse to the direction of movement of the backing material so as to break up the alignment of the longitudinal rows of tufts, reduce the affects of yarn streaking and provide patterning affects, a needle bar carrier supports the needle bar, the carrier being secured to the push rod and moving therewith and permitting the needle bar to reciprocate with the push rods yet slide relatively to the push rods.
The mounting of the needle bar for reciprocation while permitting transverse or lateral sliding movement in the prior art was originally by a support foot having a slideway within which the needle bar or a slide plate to which the needle bar was secured was mounted, the support foot being fastened to at least one push rod for reciprocation therewith. Thus, the needle bar reciprocated vertically with the support feet and could be moved laterally relative to the feet. The transverse or lateral drive for the needle bar generally is supplied by a pattern controlled shifter attachment which supplies the jogging motion to the needle bar by mechanism including a pair of rollers which straddle a plate and permits movement of the needle bar in two planes. Apparatus illustrating this construction is described in Ingram U.S. Pat. No. 4,465,001 and other prior art patents.
In order to reduce the frictional drag of the needle bar while laterally sliding, linear bearings were later mounted in the needle bar support feet with steel rods journalled in and carried by the bearings. The slide rods are clamped to blocks which in turn are secured to the needle bar so that the needle bar together with the blocks and slide rods may be moved laterally relative to the feet and push rods. Apparatus of this type is illustrated in Slattery U.S. Pat. No. 4,501,212.
As the speed of tufting machines has increased, a limitation on this speed has been the speed at which the needle bar can be shifted laterally. For example, if a tufting machine can operate with the needle bar reciprocating at 1400 to 1500 rpm, but the needle bar cannot be shifted laterally fast enough to permit running of the machine at 1200 rpm, then this lower speed is the maximum that the tufting machine with a shifter apparatus can operate. Since a substantial number of machines incorporate sliding needle bar apparatus, it has become necessary to devise apparatus for permitting the needle bar to be shifted laterally at the highest possible speeds.